When tumor tissues were fixed for 10 days, the reduction in HER2 staining intensity was more apparent, and an HER2 IHC score reduction was observed in two of three specimens in 20 % NBF and 10 % nonbuffered formalin and in three of three specimens in 20 % nonbuffered formalin (Table 5). Here, ERBB2 is linked to neoplasm.